Just a few thoughts in my post holiday depression (I supose there is always Disneyland in September)
The period between Spring break and Golden Week seems Ideal to visit the parks, still busy on weekends, but on weekdays everything in DisneySea was a walk on, weather cool but not too cold.
Fastpass is your friend. if you get one for a headiner (monsters Inc, Pooh) first thing you can pick up another about a hour after. Always make sure you have a fastpass in your pocket at al times eg before using a fastpass.... get another.
on weekend the line up before the gates open begin about 2 hours before, if you start your wait at 1 hour before you will be about half way down the line (just pass the ticket windows)
the maintainence and upkeep of the attactions is noticeably superior to the american parks
Sheraton Grand Tokyo bay is a great hotel to stay at, the monorail station is just out front and there is a great free computer centre in the lobby
if flying Jetstar be aware of bagage limits, I was two kgs above the 20kg limit leaving and returning , it cost $20 on the way and $51 on the way back.